Giandel 300w pure sinewave inverter

[Kartman]

I've got a current interest in inverter technology so i bought this unit off ebay for around $60. The non pure sinewave one was about $20 cheaper. So i spent my money and a couple of days later it turned up. The model is PC8-300S made by lingqi. The general build quality is a bit rough - there's plentynof extra solder on the board to beef up the power tracks. Pretty much a simple design - a push- pull converter using a transformer to get the 340vdc. This runs upwards of 100KHz and uses two IRF3205 mosfets and a tl494 as the pwm controller. There's a lm324 for voltage detection etc.
On the high voltage side, things get a bit more high tech. There's a PIC16F716 with a 16MHz crystal, two IR2110 mosfet drivers and 4 WFP840 mosfets arranged as a H bridge. A toroid inductor and a capacitor form the output filter. The switching freq is around 18KHz. In operation, the inductor gets a bit warm. This was only running a 32W flouro! I've yet to test at 300W. Yes, it does generate a sinewave.

Overall, it looks to be a reasonable design, but component selection is towards the cheap and cheerful side. I'd say its ok for intermittant operation but i wouldn't expect it to last long running 24/7.

[Kartman]

One thing i forgot to mention - with no load it pulls around 700mA from the supply. This is around 8W. So something is a tad lossy in there.